1. Field of the Invention
The disclosure relates in general to a resistive memory device and a method for manufacturing the same, more particularly to a resistive memory device with improved electrical characteristics and a method for manufacturing the same.
2. Description of the Related Art
A memory device such as a nonvolatile semiconductor memory device is typically designed to securely hold data even when power is lost or removed from the memory device. Various types of nonvolatile memory devices have been proposed in the related art. Also, manufactures have been looking for new developments or techniques combination for stacking multiple planes of memory cells, so as to achieve greater storage capacity. For example, several types of multi-layer stackable thin-film transistor (TFT) NAND-type flash memory structures have been proposed.
Resistive random-access memory (RRAM or ReRAM) is a non-volatile memory type. Resistive memories attract much attention due to its simple MIM (Metal-Insulator-Metal) structure and promising scalability. Different forms of ReRAM have been disclosed, based on different dielectric materials, spanning from perovskites to transition metal oxides to chalcogenides. However, the conventional resistive memory devices suffer from the defects of seams and voids in the metal layer during the fill-in procedure of the manufacture. FIG. 1 illustrates parts of a conventional resistive memory device with defects. As shown in FIG. 1, a patterned dielectric layer 12 with a via is formed on a bottom electrode 11, a barrier layer 13 is formed along the sidewalls and a bottom surface of the via within the patterned dielectric layer 12, and a metal layer 14 fills the via, followed by polishing and oxidation for growing the metal oxide as a memory layer of the resistive memory device. In the conventional metal fill-in procedure, the defects of seams 14a and/or voids 14b would be easily occurred in the metal layer 14, particularly in the center of the metal layer 14. The defects of seams 14a and/or voids 14b causes the weaker region in the metal layer 14 (i.e. the seam region, which would be easily oxidized than other regions in the metal layer 14), and the resistance variation after the oxidation process, thereby decreasing the reliability of electrical characteristics of the resistive memory device.
Thus, it would be desirable to develop and realize a resistive memory device with reliable structure and excellent electrical properties.